Unlike automobiles and motorcycles, bicycles were not originally designed with a shock absorbing suspension system. A typical bicycle usually had a standard configuration comprising a front wheel and a rear wheel connected to a bicycle frame, with the only means of shock absorption being the air in the tires.
However, as bicycle riders began placing increasing demands on their bicycles by riding through rougher terrain, such as mountain trails, they looked for better ways to prevent road surface irregularities from being transmitted to the rider. Thus, bicycle manufacturers started incorporating shock absorbing suspension systems into the design of the bicycles.
Today, it is common to see shock absorbers in the front forks of a bicycle for absorbing shocks transmitted through the front tire. Also, in bicycles with full suspension systems comprising swing arms, it is common to see the swing arm of the bicycle pivotally connected, via springs or pistons for example, to the bicycle frame in some shock absorbing manner for absorbing shocks transmitted through the rear tire.
The term "shock absorber" is used throughout this specification to refer to a spring/damper type system. It is noted that other types of shock absorbing components which serve an equivalent purpose may be used in place of a spring/damper system, and such equivalent components are intended to be encompassed by the use of the term "shock absorber."
In addition, a person of ordinary skill in the art understands that a suspension system's characteristics can refer to characteristics such as stiffness and compression rate, but are not limited solely to these characteristics.
The implementation of these shock absorbing systems provided a softer ride for the bicyclist traveling over rougher terrain, as well as better traction and control, but these systems also created new drawbacks. For example, a bicyclist will typically stand and pedal while sprinting or while climbing hills in order to deliver more power to the wheels via a pedal assembly by using the rider's entire body weight to exert downward pressure on the pedals. During these instances, the power is delivered in a cyclical, rhythmic manner that causes the bicycle to sway side-to-side and induces tremendous vertical impulses.
In most bicycles implementing a rear wheel suspension system as described above, these impulses cause the suspension system to compress and rebound, referred to as "bobbing", thus resulting in the loss of energy which would otherwise have been directed toward moving the bicycle forward.
In order to mitigate the amount of energy wasted due to this "bobbing" effect, current designs are set with the shock absorber's spring preloaded to a very high tension, with almost no sag in the setup, which in turn makes the suspension very stiff and relatively ineffective from a traction and comfort standpoint.
Thus, for the reasons stated above, there is a need and a desire for an improved suspension system for a bicycle which (1) offers a softer suspension with better traction when a rider is "in-the-saddle," an expression for describing a sitting position, or sitting on a seat, and (2) offers a stiffer suspension when a rider is, "out-of-the-saddle," an expression for describing a standing position, or not sitting on a seat.
A softer suspension is desirable for better traction and control as well as shock absorption and comfort, while a stiffer suspension is desirable for the reduction of lost "bobbing" energy, and a more efficient transfer of that energy toward the forward movement of the bicycle.